Analysis of ¹⁸O enrichment in biological fluids by continuous flow-isotope ratio mass spectrometry

Abstract

A novel method is described for the analysis of ¹⁸O in urine by continuous flow-isotope ratio mass spectrometry (CF–IRMS), after sample equilibration with CO₂. The method is shown to be fast, precise and accurate and therefore facilitates studies of total body water and water turnover in the clinical field. The method uses existing CF–IRMS instrumentation with minor hardware modification which does not compromise routine analysis of ¹³C and ¹⁵N. This method emphasizes the versatility of CF–IRMS and thus its economy for the biomedical research group using stable isotope tracers.